Hi, I had this issue and I managed to solve it. The problem is most likely inside your svg. This is what my svg looked like. It was exported from Sketch, but reopened in Illustrator:
As you can see there are quite a few layers that are unnecessary and that causes your svg to become unsharp. What I’ve done is remove everything except for what’s needed:
This solved the issue for me.
You can also Google for ‘Sketch svg blurry’ and you’ll see plenty of issues popping up. I hope this helps future Googlers into solving their issue!